Syrian tanks stormed two northwestern towns near the border with Turkey on Wednesday, expanding a military offensive to crush protests, local residents said a day after Ankara pressed Syrian President Bashar al-Assad to end killings of civilians.

At least 57 Syrian civilians were killed in armoured military assaults by President Bashar al-Assad’s forces on Sunday to crush a five-month uprising against his rule, a grassroots activists’ organisation said.

Syrian tanks tightened their occupation of Hama and massed outside a defiant city in the east as President Bashar al-Assad ignored mounting world condemnation of attacks on protesters the United States says has killed 2,000 people opposing his rule.

At least 45 civilians were killed in a tank assault by Syrian President Bashar al-Assad’s forces to occupy the centre of Hama, an activist said on Thursday, in a sharp escalation of a military campaign aimed at ending an uprising against his rule.

The death toll in Syria’s violent crackdown on opposition to President Bashar al-Assad in the city of Hama and elsewhere climbed on Tuesday, spurring Western efforts to pile diplomatic pressure on Damascus.